The present invention relates to fluids spraying assemblies used with pressure vessels.
Water spraying assemblies are used to cool gases in the dilute phase in fluid catalytic cracking (FCC) catalyst regenerator vessels. They are also used in various other processing systems. Spraying heads, or nozzles, used in spraying assemblies in FCC catalyst regenerators are subjected to an extremely harsh environment, with high temperatures and abrasion by particulate solids. The spraying heads may thus become damaged or may become detached from their water supply conduits, allowing a water stream to impinge directly on hot metal surfaces in a catalyst regenerator. In order to avoid nozzle failure of this type, it is necessary to inspect the nozzles relatively frequently. Inspection of spray nozzles must be carried out during normal operation of an FCC catalyst regenerator, while the regenerator is being used for processing hot, particulate-containing gases at a pressure of 15-25 psig. It would, of course, be impractical to shut down an FCC catalyst regenerator simply in order to inspect one or more of the water spray nozzles used in the vessel, because of the serious adverse ecomonic consequences of a shutdown.
The spray nozzles utilized in FCC regenerators are attached to one end of a straight, rigid water supply conduit, or lance, inserted into an opening into the wall of the regenerator. The water supply conduit extends outwardly through a passage typically formed by a housing attached to the wall of the regenerator, and a gate valve. The gate valve is positioned to permit closing off the passage after the nozzle and water supply conduit have been retracted past the gate. Thus, escape of hot gas from the FCC regenerator can be prevented, once the spray nozzle has been retracted to a position outside the gate of the gate valve. However, the gate valve cannot be closed until the conduit and spray nozzle have been retracted.
Previously, in order to permit retraction of a spray nozzle and water supply conduit, while simultaneously preventing leakage of gas from the generator during nozzle retraction, a packing gland has been employed. The packing gland surrounded the water supply conduit, and closed off the exterior opening of the passage. A packing gland does allow the nozzle and conduit to be retracted, but the substantial friction involved in moving the supply conduit through the packing gland has made it very difficult and time-consuming to retract or insert the water supply conduit. In order to move the conduit to retract the spray nozzle to a position outside the gate of the gate valve, it has been necessary for several persons to carry out the retraction procedure, and nozzle inspection has taken an inordinately long period of time to accomplish. The present invention permits the nozzle and water supply conduit to be easily and quickly retracted for inspection without leakage of hot regeneration gases from an FCC catalyst regenerator. Further, the present invention allows the conduit and spray nozzle to be quickly and easily replaced in position for spraying use in the FCC regenerator vessel without leakage of hot gases.